gpio: Use an 'ops' variable everywhere

Update this driver to use the common method of putting the driver
operations in an 'ops' variable install of calling gpio_get_ops()
repeatedly. Make it const since operations do not change.

Signed-off-by: Simon Glass <sjg@chromium.org>

Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
1 file changed